?php
 /***************************************************************************************
 *php BC高精確度函數(shù)庫
 *php bc math 包含了：相加，比較，相除，相減，求余，相乘，n次方，配置默認(rèn)小數(shù)點(diǎn)數(shù)目，求平方
 *這些函數(shù)在涉及到有關(guān)金錢的計(jì)算時(shí)比較有用
 ***************************************************************************************
 *兩個(gè)高精度數(shù)比較
 *工作中遇到一種情況，0.00 ！= 0
 *int bccomp ( string $left_operand , string $right_operand [, int $scale ] )
 *$left=$right 返回 0
 *$left$right 返回 -1
 *$left>$right 返回 1
 *$scale 小數(shù)點(diǎn)位數(shù)
 ***************************************************************************************/
$a = 4.45;
$b = 5.54;
if(bccomp($a, $b, 2) == 0)
{
 echo "完全相等";
}
/***************************************************************************************
 *兩個(gè)高精度數(shù)相加
 *string bcadd ( string $left_operand , string $right_operand [, int $scale ] )
 *$scale 返回的小數(shù)點(diǎn)個(gè)數(shù)
 ***************************************************************************************/
$a = 1.0321456;
$b = 0.0123456;
$c = bcadd($a, $b, 2);
var_dump($c);
/***************************************************************************************
 *兩個(gè)高精度數(shù)相減
 *sstring bcsub ( string $left_operand , string $right_operand [, int $scale ] )
 *$scale 返回的小數(shù)點(diǎn)個(gè)數(shù)
 ***************************************************************************************/
$a = 1.0321456;
$b = 3.0123456;
$c = bcsub($a, $b, 2);
var_dump($c);
/********************************************************
 *兩個(gè)高精度數(shù)求余/取模
 *string bcmod ( string $left_operand , string $modulus )
 *******************************************************/
$a = 6;
$b = 4;
$c = bcmod($a, $b);
var_dump($c);
/***************************************************************************************
 *兩個(gè)高精度數(shù)相除
 *string bcdiv ( string $left_operand , string $right_operand [, int $scale ] )
 *$scale小數(shù)點(diǎn)位數(shù)默認(rèn)為 0
 ***************************************************************************************/
 $a = 6;
 $b = 5;
 $c = bcdiv($a, $b, 3);
 var_dump($c);
/***************************************************************************************
 *兩個(gè)高精度數(shù)相乘
 *string bcmul ( string $left_operand , string $right_operand [, int $scale ] )
 *$scale小數(shù)點(diǎn)位數(shù)默認(rèn)為 0
 ***************************************************************************************/
$a = 3.1415926;
$b = 2.4569874566;
$c = bcmul($a, $b, 6);
var_dump($c);
/***************************************************************************************
 *兩個(gè)高精度數(shù)的次方值
 *string bcpow ( string $left_operand , string $right_operand [, int $scale ] )
 *$scale小數(shù)點(diǎn)位數(shù)默認(rèn)為 0
 ***************************************************************************************/
$a = 3.1415926;
$b = 2;
$c = bcpow($a, $b, 3);
var_dump($c);
/**************************************************
 *求高精度數(shù)的平方根
 *string bcsqrt ( string $operand [, int $scale ] )
 *$scale小數(shù)點(diǎn)位數(shù)默認(rèn)為 0
 ***************************************************/
$b = bcsqrt($a, 6);
var_dump($b);
/******************************
 *設(shè)置bc函數(shù)的小數(shù)點(diǎn)位數(shù)
 *bool bcscale ( int $scale )
 *$scale小數(shù)點(diǎn)位數(shù)默認(rèn)為 0
 ******************************/
bcscale(2);
?>

string(4) "1.04"
string(5) "-1.98"
string(1) "2"
string(5) "1.200"
string(8) "7.718853"
string(5) "9.869"
string(8) "1.772453"